ios webView加载html适应手机屏幕的问题

webView加载html，如图：

html文件被放大了，没有适应手机屏幕，调了js处理： 
NSString *js_fit_code = [NSString stringWithFormat:@"var meta = document.createElement('meta');"
        "meta.name = 'viewport';"
        "meta.content = 'width=device-width, initial-scale=1.0,minimum-scale=0.1, maximum-scale=2.0, user-scalable=yes';"
        "document.getElementsByTagName('head')[0].appendChild(meta);"
                               ];
 [webView stringByEvaluatingJavaScriptFromString:js_fit_code];